Bull Bitcoin Adds Payjoin Privacy to Exchange Transactions

Bull Bitcoin expands Payjoin across exchange activity

Bull Bitcoin has announced that its exchange supports Payjoin for Bitcoin deposits and withdrawals, describing itself as the first Bitcoin exchange to offer those options. The company also introduced Payjoin-by-default trading, a setup in which eligible on-chain purchases and sales made through its BULL Wallet use the privacy protocol automatically. The announcement expands Payjoin from a wallet feature into exchange activity, though the company’s first-in-the-world description is its own claim.

Founded in Canada by Francis Pouliot in 2013, Bull Bitcoin describes itself as a Bitcoin-only exchange and says it serves customers in Canada, Europe and Latin America. Its platform is non-custodial: customers can buy Bitcoin directly to their own wallet and sell Bitcoin to a bank account. The company also develops BULL Wallet, a free, open-source, self-custodial Bitcoin wallet, and says it has funded itself since it began.

That non-custodial structure is central to the announcement. Bull Bitcoin says each exchange trade leaves an on-chain transaction trail, so a trade is visible on the Bitcoin network even though customers hold their own coins. The new integration is intended to alter what observers can infer from that trail. It does not make transactions disappear; rather, Payjoin changes transaction patterns that chain-analysis tools commonly interpret as clues about a sender’s activity.

How Payjoin changes transaction patterns

Payjoin is an on-chain Bitcoin privacy protocol that adds an off-chain coordination step between participants. The source explains that it is designed to challenge assumptions such as treating one transaction output as change returning to the sender. It can also make the amounts sent and returned less revealing of the users’ intentions. Since Bitcoin transaction amounts are public, changing those patterns may make it harder to connect a payment with a particular purpose.

The protocol’s value, as described by Bull Bitcoin, is not limited to concealing whether an output is change. The company says Payjoin can reduce round-number transaction amounts and address reuse, making it harder for outside observers to estimate a payment’s fiat value. The source also notes that public amounts can expose clues about financial habits, including salary information or a pattern such as dollar-cost averaging. These are potential inferences, not information Payjoin guarantees will remain hidden.

Payjoin does not require changes to Bitcoin’s consensus rules through either a hard fork or a soft fork. Instead, wallets and exchanges need to adopt it for broader use. The source says individual users can benefit without waiting for collective network-wide adoption, while wider participation can make common-input ownership and change-output heuristics less dependable. The distinction matters: adoption can improve the protocol’s reach, but the feature can still be useful on an individual basis.

Default use links privacy with wallet management

Under the default setting, a BULL Wallet user who buys or sells Bitcoin on-chain through the wallet’s built-in exchange will have a Payjoin transaction. Bull Bitcoin says this removes the need for customers to manually initiate the privacy step for those trades. The automatic design may make use more accessible to people who do not know how transaction construction affects privacy, although the announcement does not specify exceptions or detail how every transaction is handled.

The company also presents Payjoin-by-default as a way to manage wallet outputs, known as UTXOs. Its explanation says that users may periodically spend coins to a new address to combine or consolidate outputs, which can reduce the size and cost of later transactions. Payjoin is intended to automate this kind of aggregation in connection with wallet trades. Any fee benefit is prospective: the source describes possible lower future mining fees, not a guaranteed saving on every transaction.

Bull Bitcoin links this wallet-level use to effects on the wider network. It says reducing the Bitcoin UTXO set can make it easier for people to run a node and may ease fee pressure for users. The announcement therefore frames default Payjoin as both a privacy feature and a form of routine output management. It does not quantify how much consolidation will occur, how large any fee effects might be, or how quickly broader network benefits could appear.

Open-source development and remaining uncertainties

The exchange feature builds on earlier work in BULL Wallet. In December 2024, the wallet became, according to the source, the first Bitcoin wallet to integrate Payjoin V2. That effort was described as highly experimental and was coordinated with Dan Gould and the Payjoin Dev Kit team, whose members later founded the Payjoin Foundation. Researchers used lessons from that experimentation to improve the user experience and make it more resistant to attacks.

Bull Bitcoin says the software powering Payjoin in both the wallet and exchange is free and open-source. The company’s integration is based closely on work by the Payjoin Foundation, connecting the exchange rollout to development outside the company as well as its own wallet project. The source does not provide independent performance testing, usage figures or technical comparisons with other exchanges, so the practical effect at scale remains to be established.

To use the features, the announcement says customers need to download BULL Wallet, create a Bull Bitcoin exchange account and log into that account through the mobile app; the rest is described as automatic. That outlines the company’s intended onboarding path, but leaves questions about availability by region, transaction eligibility and user controls unanswered. The broader privacy gains also depend on adoption: Bull Bitcoin argues that more use can benefit the network, but gives no forecast for uptake.

Source: BitcoinMagazine